1. Field of the Invention
The present invention relates to a decorative photosensitive film for producing a capacitance type input device capable of detecting a touch position of a finger as a change of capacitance, a method for producing a capacitance type input device, a capacitance type input device obtained by the production method, and an image display apparatus equipped with the capacitance type input device as a constitutional component.
2. Background Art
In recent years, electronic equipments, such as mobile telephones, car navigation systems, personal computers, ticket vending machines and banking terminals, include ones that are equipped with a tablet type input device on a surface of a liquid crystal display device or the like, in which an indicating image is displayed on an image display region of the liquid crystal display device, and the position where the indicating image is displayed is touched with a finger, a stylus pen or the like by referring to the indicating image, thereby enabling input of information corresponding to the indicating image.
The input device (i.e., a touch-sensitive panel) includes a resistive film type, a capacitance type and the like. However, the resistive film type input device has a two-layer structure containing a film and a glass plate, in which the film is pressed down to short-circuit them, and thus has disadvantages including the narrow operative temperature range and the time-lapse deterioration.
On the other hand, the capacitance input device has such an advantage that a translucent conductive film may be simply formed on a single substrate. The capacitance input device includes, for example, such a type that has electrode patterns that extend to cross each other, and on touching the electrodes with a finger or the like, the change of the capacitance between the electrodes is detected to determine the input position (see, for example, Patent Literature 1).
The capacitance input device also includes such a type that alternating currents having the same phase and the same potential are applied to both ends of the translucent conductive film, and on forming a capacitor by touching with a finger or bringing a finger close thereto, a weak electric current flowing is detected to determine the input position. As the capacitance type input device of this type, such a capacitance type input device is disclosed that contains plural first transparent electrode patterns formed of plural pad portions formed to extend in a first direction and connected through connecting portions, and plural second transparent electrode patterns electrically insulated from the first transparent electrode patterns with an interlayer insulating layer, and formed of plural pad portions formed to extend in a direction intersecting the first direction (see, for example, Patent Literature 2). However, the capacitance type input device has a front plate laminated on the capacitance type input device produced, and thus has a problem including the large thickness and the large weight of the capacitance input device.
A capacitance type touch-sensitive panel containing a front plate having on a non-contact surface thereof a mask layer, a sensor circuit and an interlayer insulating layer, which are integrated, is disclosed (see, for example, Patent Literature 3). The capacitance type touch-sensitive panel of Patent Literature 3 has the front plate and the capacitance type input device, which are integrated to each other, and thus has a small thickness and a light weight, and a decorative layer having various color tones (such as black, white, pastel colors and metallic colors) may be provided depending on necessity between the mask layer and the front plate, among which a white decorative layer is demanded to be enhanced in brightness and whiteness.
As the method for providing the decorative layer, methods of coating a liquid resist, screen printing and the like are mainly employed.
For a smartphone and a tablet PC having a capacitance type touch-sensitive panel on a liquid crystal display device or an organic EL display device, on the other hand, ones using toughened glass represented by Gorilla Glass, available from Corning Inc., as a front panel (i.e., a surface that is touched directly with a finger) have been developed and announced.
On forming a white decorative layer on the substrate with a liquid resist or a screen printing ink for forming a decorative layer, it is necessary to perform application of the liquid resist or screen printing multiple times for forming the white decorative layer with a liquid resist or a screen printing ink having small hiding power, thereby causing such a problem that bubbles and unevenness occur, and difficulty in cost reduction due to the increased number of process steps.